n-butylamine(I), diethylamine (II) and N,N-dimethylethylamine (III) have the same molar mass. The increasing order of their boiling point is

Options

A. `IIIltIIltI`
B. `IltIIltIII`
C. `IIltIIIltI`
D. `IIltIltIII`

Answer

A

Explanation

`underset("n-Butylamine(Primary amine)")(H_(3)C-CH_(2)-CH_(2)-NH_(2))`
`underset("Diethylamine (Secondary amine)")(CH_(3)CH_(2)-NH-CH_(2)-CH_(3)),underset("Ethyldimethylamine (Tertiary amine)")(CH_(3)-overset(CH_(3))overset(|)(N)-C_(2)H_(5))`
Primary amines have two hydrogen atoms available for hydrogen bond formation, while `2^(@)` amines have only one. hydrogen atom for hydrogenbond formation `3^(@)` amines do not have intermolecular association due to absence of hydrogen atom. Thus, order of boiling point of isomeric amines is as follows `3^(@)lt2^(@)lt1^(@)` or `IIIltIIltI`.